Masterbatch method for processing polyester resin and articles thereof

ABSTRACT

The present invention provides a masterbatch method for producing a polyester resin and articles thereof; comprising reacting following materials uniformly at a temperature equal to or greater than the melting point of a polyester, the materials comprising: (1) 100 parts by weight of saturated straight-chain polyester A; (2) 1 to 10 parts by weight of binder masterbatch D comprising: a mixture containing a compound having two epoxy groups and a compound having an average number of epoxy groups of 2.1 or more; (3) 0.25 to 10 parts by weight of catalyst masterbatch G comprising: a metal carboxylate, whereby the melt viscosity of the polyester increases so that the melt flow rate (MFR) becomes 50 g/10 min or less, and the degree of swelling of the polyester increases to between 5% and 200%, thus resulting in a high-quality resin having excellent mechanical properties. The resin can be advantageously used for films, sheets, foamed materials, pipes, cushioning, heat insulators, packing materials, and so forth.

TECHNICAL FIELD

The present invention relates to masterbatch methods for producinghigh-quality polyester resins having improved processability andarticles thereof by uniformly subjecting a straight-chain polyesterresin having relatively low molecular weight to a coupling reaction toincrease the melt viscosity and the degree of swelling, using a smallamount of binder masterbatch and a trace amount of catalyst masterbatch.More specifically, the present invention relates to a masterbatch methodfor producing a high-quality polyester resin having improvedprocessability and articles of the polyester resin by subjecting arecycled polyethylene terephthalate-based polyester whose molecularweight and mechanical properties have been reduced to a couplingreaction to increase the molecular weight, the melt viscosity, and thedegree of swelling while preventing the byproduction of gel andfisheyes.

BACKGROUND ART

In polyesters, saturated straight-chain polyesters (hereinafter,referred to as PET-based polyesters), such as polyethylene terephthalate(PET), polybutylene terephthalate (PBT),polyethylene-2,6-naphthalenedicarboxylate (PEN), and PETG, haveexcellent characteristics and are, therefore, widely used for fibers,films, bottles, and the like. Also, the PET-based polyesters are usedextensively as high-performance resin materials in many industrialfields, such as the automotive, machine, electrical and electronicmaterial, construction material, and container industries.

From the viewpoint of resource saving and environmental conservation, ithas recently been understood that waste plastics collected frommanufacturing processes and public consumer markets must be recycled. Asfor the PET-based polyesters, waste bottles, films, sheets, fibers, andthe like have also been actively recycled accordingly. However, in thesePET-based polyesters, heat treatment in molding processes is liable tosignificantly reduce the molecular weight thereof and to increase thenumber of carboxyl radicals at ends of the molecules thereof. This is abottleneck in the development of recycling techniques of collectedpolyesters. The molecular weight of collected waste PET-based polyestersis lower than that of a new chip. For example, the molecular weight offlakes (fragments) of recycled PET bottles, which are generated in largequantity, is reduced to substantially half the original molecularweight. Therefore, if such PET bottles are reused as a base resin,processability is degraded. The resin results in, at the best, fibers,which can be produced even from a low-molecular-weight base resin, orlow-quality sheets, and thus the resulting products do not have thequality satisfying requirements of the original PET bottles or otherfilms and sheets. Thus, the use of recycled PET-based polyesters hasnarrow limits.

On the other hand, plastic articles featuring light weight, elasticity,processability, and the like have recently been used for packingcontainers and cushioning in large quantity. If the molecular weight andmelt viscosity of the flakes of low-molecular-weight recycled PETbottles or new PET are increased, inexpensive articles can be achieved.

Some methods are known as solutions for these challenges, includingmethods in which solid phase polymerization is performed to restore themolecular weight; a terminal group of the polyester is allowed to reactwith a chain-extending agent (binder) to increase the molecular weight;or another resin, such as an elastomer, is added to compensate for themechanical properties.

It is proposed that, as the chain-extending agent (binder), a compoundhaving a functional group, such as isocyanate, oxazoline, epoxy,aziridine, or carbodiimide be used. However, the chain-extending agentis subjected to strong constraints from the viewpoint of reactivity,thermal stability, and stability. Applicable chain-extending agents are,therefore, limited to specific compounds. Epoxy compounds are relativelyuseful as the chain-extending agent, and a monoepoxy compound (JapaneseUnexamined Patent Application Publication No. 57-161124) and diepoxycompounds (Japanese Patent Application laid open No. 7-166419 andJapanese Patent Application laid open Nos. 48-25074 and 60-35944) areknown. However, these epoxy compounds have problems with reactionvelocity, formation of gel, melt viscosity, compatibility, thermalstability, physical properties of the resulting articles, and the like,and have not yet been put into practical use.

On the other hand, a method for increasing the molecular weight ofpolyester is proposed (PCT Japanese laid open No. 8-508776) in whichcollected waste PET-based polyester is melted and mixed with adifunctional epoxy resin and hydroxyphenylalkylphosphonate having sterichindrance effects. Unfortunately, the sterically hinderinghydroxyphenylalkylphosphonate is expensive though this method makesreaction velocity faster. This is a problem in practical use forindustries which need low-cost recycling. Although another method hasalso been proposed in which rubber and an elastomer are added to thepolyester, this method has problems with characteristics after drying,compatibility, thermal stability, elasticity, and the like.

In general, plastics used for various types of articles are polystyrene,polyethylene, and polypropylene having high molecular weights and highmelting viscosities. The melting point of PET-based polyesters is as lowas about 2,000 poise at 280° C., even if the molecular weight thereof isincreased (to, for example, an intrinsic viscosity of 1.0 dl/g, anumber-average molecular weight of about 17,000, and a weight-averagemolecular weight of about 44,000) to use for bottles and, therefore, itis difficult to form the PET-based polyester into various types ofarticles for many applications as in polyolefins The inventors of thepresent invention have proposed a method for producing a PET-basedpolyester resin having a long chain, blanched structure andcharacteristic features of having a high molecular weight, a high melttension, a high degree of swelling and the like and an article of thePET-based resin (PCT WO 98/44019) by adding both difunctional andtrifunctional epoxy compounds, acting as a small amount of binder, and atrace amount of coupling reaction catalyst to the PET-based polyester inadvance, and conducting a rapid reaction for about two minutes in anextruder. In this method, however, a local reaction at the ditch of thescrew and vicinity of vent the extruder where the raw andhigh-concentration binder and catalyst have been placed is liable tointensely produce gel as a by product, and thus continuous operation formore than several hours causes gel and fisheyes. It has been found thatthe quality of, for example, tubular films, thin films produced by aT-die method, and foamed sheets and pipes is liable to be degraded dueto large amounts of gel and fisheyes and, therefore, the prior inventionhas not been perfected.

In order to solve the problem of causing gel and fisheyes resulting fromthe local reaction during the rapid reaction of the binder and thecatalyst in an extruder, an object of the present invention is toprovide a masterbatch method for producing a polyester resin having animproved processability and an article of the polyester resin in whichthe molecular weight of a brittle PET-based polyester of, particularly,recycled PET bottles having a relatively low molecular weight isincreased, and the melt viscosity of the polyester is also increased sothat various types of molding can be performed.

DISCLOSURE OF THE INVENTION

The inventors of the present invention have conducted intensive researchto accomplish this object, and consequently found that the known methodfor producing the PET-based polyesters having a specific molecularweight and the characteristic features of high melt viscosity and largeswelling and which are made suitable for tubular films, tough sheets,foamed sheets, and directly blown bottles and pipes by adding a specificepoxy resin, acting as a binder, and a coupling reaction catalyst to asaturated polyester is liable to by-produce gel resulting from a localreaction in the vicinity of high-concentrations of raw binder andhigh-concentrations of raw catalyst. The inventors have redoubled theireffort to devise an advantageous method. As a result, they found that amasterbatch method in which masterbatches each previously diluted in abase substance are allowed to uniformly react with a saturated polyesteracting as a raw material can solve the problem, with industrialadvantages, and thus achieved the present invention.

Specifically, the present invention is, first, directed to a masterbatchmethod for producing a polyester resin, comprising the step of allowingthe following materials to react uniformly:

(1) 100 parts by weight of saturated straight-chain polyester A;

(2) 1 to 10 parts by weight of binder masterbatch D comprising: 10 to 50parts by weight of a mixture B acting as a binder containing 0 to 100parts by weight of a compound having two epoxy groups in the moleculethereof and 100 to 0 parts by weight of a compound having an averagenumber of epoxy groups of 2.1 or more; and 100 parts by weight of basesubstance C; and

(3) 0.25 to 10 parts by weight of catalyst masterbatch G comprising 5 to25 parts by weight of a metal carboxylate acting as coupling reactioncatalyst E and 100 parts by weight of base substance F.

The coupling reaction is performed at a temperature more than or equalto the melting point of the polyester. Thus, the melt viscosity of thepolyester increases so that the melt flow rate (MFR) is 50 g/10 min orless at 280° C. and under a load of 2.16 kgf in accordance withcondition 20 of JIS K 7210, and the degree of swelling of the polyesterincreases to between 5% and 200%.

Second, the present invention is directed to a masterbatch method forproducing an article, comprising the steps of molding a polyester resinprepared by the above-described method into pellets in advance; andmolding the pellets into the articles.

Third, the present invention is directed to a masterbatch method forproducing an article, comprising the step of introducing a polyesterresin prepared by the above-described method to a die or a mold to formthe articles immediately after the coupling reaction.

Fourth, a masterbatch method for producing a polyester resin or anarticle of the polyester resin according to any one of the methodsdescribed above is provided in which saturated straight-chain polyesterA is a polyethylene terephthalate-based aromatic polyester having anintrinsic viscosity in the range of 0.50 to 0.90 dl/g.

Fifth, a masterbatch method for producing a polyester resin or anarticle of the polyester resin according to any one of the methodsdescribed above is provided in which saturated straight-chain polyesterA is a recycled material prepared from a collected polyethyleneterephthalate-based aromatic polyester articles.

Sixth, a masterbatch method for producing a polyester resin or anarticle of the polyester resin according to any one of the methodsdescribed above is provided in which the compound having two epoxygroups in the molecule thereof contained in binder B of bindermasterbatch D contains at least one selected from the group consistingof aliphatic polyethylene glycol diglycidyl ether, alicyclichydrogenated bisphenol A diglycidyl ether, and aromatic bisphenol Adiglycidyl ether and early condensates of bisphenol A diglycidyl ether.

Seventh, a masterbatch method for producing a polyester resin or anarticle of the polyester resin according to any one of the methodsdescribed above is provided in which the compound having an averagenumber of epoxy groups of 2.1 or more contained in binder B of bindermasterbatch D contains at least one selected from the group consistingof: aliphatic trimethylolpropane triglycidyl ether, glycerin triglycidylether, epoxide soybean oil, and epoxide linseed oil; heterocyclictriglycidyl isocyanurate; and aromatic phenol novolac epoxy resins,cresol novolac epoxy resins, and bisresorcinol tetraglycidyl ether.

Eighth, a masterbatch method for producing a polyester resin or anarticle of the polyester resin according to any one of the methodsdescribed above is provided in which base substance C of bindermasterbatch D contains at least one selected from the group consistingof a polyethylene terephthalate-based aromatic polyester having anintrinsic viscosity in the range of 0.50 to 0.90 dl/g, a recycledmaterial prepared from a collected polyethylene terephthalate-basedaromatic polyester articles, condensates of ethylene glycol,cyclohexanedimethanol, and terephthalic acid, polyethylene acrylateresins, and toluene.

Ninth, a masterbatch method for producing a polyester resin or anarticle of the polyester resin according to any one of the methodsdescribed above is provided in which coupling reaction catalyst E ofcatalyst masterbatch G is a composite containing at least two selectedfrom the group consisting of lithium salts, sodium salts, potassiumsalts, magnesium salts, calcium salts, zinc salts, and manganese saltsof stearic acid and acetic acid.

Tenth, a masterbatch method for producing a polyester resin or anarticle of the polyester resin according to any one of the methodsdescribed above is provided in which base substance F of catalystmasterbatch G contains at least one selected from the group consistingof a polyethylene terephthalate-based aromatic polyester having anintrinsic viscosity in the range of 0.50 to 0.90 dl/g, a recycledmaterial prepared from a collected polyethylene terephthalate-basedaromatic polyester articles, condensates of ethylene glycol,cyclohexanedimethanol, and terephthalic acid, and polyethylene acrylateresins.

Eleventh, the present invention is directed to a masterbatch method forproducing polyester resin pellets, comprising the steps of: melting (1)undried saturated straight-chain polyester A at a temperature more thanor equal to the melting point thereof while performing dehydration bydegassing to a pressure of 13.3×10³ Pa or less in a non-water-sealedvacuum line; allowing (2) binder masterbatch D and (3) coupling reactioncatalyst masterbatch G to uniformly react together by heating. Thus, theresulting polyester resin has a melt flow rate (MFR) of 50 g/10 min orless at a temperature of 280° C. under a load of 2.16 kgf in accordancewith condition 20 of JIS K 7210, and has a degree of swelling of 5% to200%. The step of pelletizing the resulting polyester resin is alsoperformed.

Twelfth, the present invention is directed to a masterbatch method forproducing an article, comprising the steps of: melting (1) undriedsaturated straight-chain polyester A at a temperature more than or equalto the melting point thereof while performing dehydration by degassingto a pressure of 13.3×10³ Pa or less in a non-water-sealed vacuum line;allowing (2) binder masterbatch D and (3) coupling reaction catalystmasterbatch G to uniformly react together by heating. Thus, theresulting polyester resin has a melt flow rate (MFR) of 50 g/10 min orless at a temperature of 280° C. under a load of 2.16 kgf in accordancewith condition 20 of JIS K 7210, and has a degree of swelling of 5% to200%. The step of introducing the resulting polyester to a die or a moldto form the articles immediately after the foregoing coupling reactionis also performed.

BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, saturated straight-chain polyester A ofcomponent (1), acting as a raw material prepolymer, is synthesized froma dicarboxylic acid component and a glycol component, or from ahydroxycarboxylic acid. Exemplary dicarboxylic acid components includearomatic dicarboxylic acids, such as terephthalic acid, isophthalicacid, naphthalenedicarboxylic acid, diphenylcarboxylic acid,diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid,diphenyletherdicarboxylic acid, methylterephthalic acid, andmethylisophthalic acid; and aliphatic or alicyclic dicarboxylic acid,such as succinic acid, adipic acid, sebacic acid, decanedicarboxylicacid, dodecanedicarboxylic acid, and cyclohexanedicarboxylic acid. Inthese dicarboxylic acids, aromatic dicarboxylic acids, particularlyterephthalic acid and 2,6-naphthalenedicarboxylic acid, are preferable.

Exemplary glycol components include ethylene glycol, trimethyleneglycol, tetramethylene glycol, hexamethylene glycol, decamethyleneglycol, neopentyl glycol, cyclohexanedimethanol, polyoxyethylene glycol,polyoxypropylene glycol, and polyoxytetramethylene glycol. In theseglycols, ethylene glycol, tetramethylene glycol, cyclohexanedimethanolare preferable.

Exemplary hydroxycarboxylic acids include α-hydroxycaproic acid,hydroxybenzoic acid, and hydroxyethoxybenzoic acid.

Practical examples of saturated straight-chain polyester A includepolyethylene terephthalate (PET), polybutylene terephthalate (PBT),polyethylene-2,6-naphthalate (PEN), PETG (produced by Eastman), andtheir copolymers. Since polyethylene terephthalate (PET) has beenmass-produced worldwide and the recycling system thereof is beingcompleted, PET is particularly suitable for the raw material prepolymerof the present invention.

Preferably, saturated straight-chain polyester A used as the prepolymerof the present invention has an intrinsic viscosity (IV value) of 0.50dl/g (this value corresponds to a melt flow rate (MFR) of about 210 g/10min or less at 280° C. and under a load of 2.16 kgf in accordance withJIS K 7210), and more preferably 0.60 dl/g or more (an MFR of about 130g/10 min or less) when the intrinsic viscosity is measured at 25° C.after dissolving the prepolymer in the 1,1,2,2-tetrachlorethane:phenol(1:1) solvent mixture. If the intrinsic viscosity is less than 0.50dl/g, it is difficult to increase the molecular weight and the meltviscosity even according to the present invention. The resultingpolyester is likely not to have excellent processing characteristics offoaming. The intrinsic viscosity does not have a specific upper limit,but preferably, it is limited to 0.90 dl/g (MFR of about 25 g/10 min ormore), and more preferably to 0.80 dl/g (MFR of about 45 g/10 min ormore).

In practice, flakes or pellets of PET-based polyester bottles collectedin large quantity are often used as the prepolymer. PET bottlesgenerally have relatively high intrinsic viscosities, and accordingly,the intrinsic viscosity of collected PET bottles is high, and isgenerally 0.60 to 0.80 dl/g (MFR of 130 to 45 g/10 min), andparticularly 0.65 to 0.75 dl/g (MFR of 100 to 55 g/10 min).

When recycled polyester articles are used, the polyester articles may befibers, films, bottles, or other articles, and the polyester may containa small amount of another polymer, such as polyolefin or polyacrylicester. Also, the polyester may contain a small amount of additives suchas a filler, a pigment, and a dye. In general, flakes (fragments) ofrecycled PET bottles are supplied in a paper bag containing 20 kg or aflexible container containing 500 kg, and the flakes generally contains3,000 to 6,000 ppm (0.3% to 0.6% by weight) of water.

Binder B of component (2) of the present invention is a compound havingtwo epoxy groups or, in some cases, an average number of epoxy groups of2.1 or more. Exemplary compounds having two epoxy groups on averageinclude aliphatic compounds, such as polyethylene glycol diglycidylether, polypropylene glycol diglycidyl ether, tetramethylene glycoldiglycidyl ether, 1,6-hexamethylene glycol diglycidyl ether, neopentylglycol diglycidyl ether, and glycerin diglycidyl ether; alicycliccompounds, such as hydrogenated bisphenol A diglycidyl ether,hydrogenated isophthalate diglycidyl ester,3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, andbis(3,4-epoxycyclohexyl)adipate; heterocyclic compounds, such asdiglycidyl hydantoin and diglycidyl oxyalkyl hydantoin; and aromaticcompounds, such as bisphenol A diglycidyl ether, early condensate ofbisphenol A diglycidyl ether, diphenylmethane diglycidyl ether,terephthalate diglycidyl ester, isophthalate diglycidyl ester, anddiglycidyl aniline.

Exemplary compounds B having three epoxy groups on average includealiphatic compounds, such as trimethylolpropane triglycidyl ether andglycerin triglycidyl ether; heterocyclic compounds, such as triglycidylisocyanurate, triglycidyl cyanurate, and triglycidyl hydantoin; andaromatic compounds, such as triglycidyl para- or meta-aminophenol.

Exemplary compounds B having four epoxy groups on average includetetraglycidylbenzylethane, sorbitol tetraglycidyl ether, tetraglycidyldiaminophenylmethane, and tetraglycidyl bisaminomethylcyclohexane.

Compound B having a mixed decimal number of epoxy groups between 2.1 andseveral pieces on average may be phenol novolac epoxy resins and cresolnovolac epoxy resins. Dow Chemical Company places exemplary compounds Bhaving 2.2, 3.6, 3.8 and 5.5 epoxy groups on average on the market, andthese are available.

In order to be used for food packaging, the epoxy resins must be verysafe. Preferably, epoxide soybean oil (Adekasizer O-130P), epoxidelinseed oil (Adekasizer O-130P), or epoxide fatty alkyl ester(Adekasizer D-178) manufactured by Asahi Denka Co., Ltd. and certifiedby the FDA, the heat-stable epoxy resin NC-3000S (negative in the AIMStest) manufactured by Nippon Kayaku Co., Ltd., or the like are used.

The content of compound B of component (2) having epoxy groups of thepresent invention is in the range of 0.1 to 5 parts by weight to 100parts by weight of the saturated straight-chain polyester of component(1). Preferably, it is in the range of 0.4 to 1.0 parts by weight. Ifthe content is less than 0.1 parts by weight, compound B does notsufficiently serve to extend chains, and the molecular weight and themelt viscosity do not increase enough. Consequently, the processabilityis not improved. In contrast, if the content is more than 5 parts byweight, the fundamental and mechanical characteristics and theelasticity of the resulting articles decrease by the effect ofplasticizer, or large amounts of gel and fisheyes bring out. In general,the content depends on the type of component (2), and particularly onthe molecular weight. For example, if an epoxy resin having a lowmolecular weight and an epoxy equivalent of 100 to 200 g/eq is allowedto react with a saturated straight-chain polyester having a highintrinsic viscosity of 0.90 dl/g, a component B content of 0.1 parts byweight will suffice. If an epoxy resin having a high molecular weightand an epoxy equivalent of 2000 g/eq is allowed to react with asaturated straight-chain polyester having a low intrinsic viscosity of0.50 dl/g, a component B content of about 5 parts by weight may benecessary.

The present invention is characterized in that a mixture containing 0%to 100% by weight of a compound having two epoxy groups and 100% to 0%by weight of a compound having an average number of polyfunctional epoxygroups of 2.1 or more is used as binder B, thereby increasing themolecular weight of the saturated straight-chain polyester andintroducing a long-chain branch. Thus, a PET-based polyester having ahigh melt viscosity and a high degree of swelling, which are necessaryto form tubular films, direct blown bottles, highly foamed materials,pipes, and the like, and various articles of the PET-based polyester canbe achieved. According to the present invention, by increasing thealternatives and usage of compound B containing a compound having 2polyfunctional epoxy groups and a compound having an average number ofpolyfunctional epoxy groups of 2.1 or more, the number of long branchedchains, the molecular weight, the melt viscosity, the degree ofswelling, and the like can be controlled to a level at which varioustypes of molding can be conducted. The polyester of the presentinvention allows molecular chains to entangle each other because of theintroduction of a long-chain branch. Thus, the degree of swelling andthe melt viscosity can be arbitrarily increased even if the intrinsicviscosity is relatively low and in the range of 0.6 to 0.8 dl/g.

Preferably, in the present invention, a mixture of 0% to 99% by weightof the compound having two epoxy groups in the molecule thereof and 1%to 100% by weight of the compound having an average of at least 2.1 ofpolyfunctional epoxy groups in the molecule thereof is used. Thecompound having two epoxy groups mainly serves to increase the molecularweight of the saturated straight-chain polyester and reduce the MFR. Onthe other hand, the compound having an average of at least 2.1 ofpolyfunctional epoxy groups also serves to increase the molecular weightand reduce the MFR. In addition, it mainly serves to form a long-chainbranch to increase the degree of swelling and the melt viscosity. As aresult, tubular films, directly blown bottles, tough sheets, highlyfoamed materials, and pipes can be arbitrarily produced. Under presentcircumstances, for tubular films and pipes and directly blown bottles,for example, a PET-based polyester having a relatively small number oflong-chain branches, an MFR of 3 g/10 min or less, and about 20% to 50%of swelling is preferable. For highly expanded foamed materials, forexample, a PET-based polyester having a large number of long-chainbranches, an MFR of 3 to 10 g/10 min, and about 50% to 200% of swellingis preferable. For tough sheets capable of two times or more deeperstretching than commercially available A-PET, for example, a PET-basedpolyester having a relatively large number of long-chain branches, anMFR of 5 to 20 g/10 min, and about 50% to 100% of swelling ispreferable.

One of the most striking characteristics of the present invention isthat binder masterbatch D prepared by previously diluting binder B withbase substance C is used in order to prevent the raw material polyesterfrom locally reacting with raw and high-concentration binder B, as inthe manner in which, for example, homogeneous kuzu-yu is prepared bypouring hot water into kuzu starch previously dispersed in water. Asbase substance C, a polyethylene terephthalate-based aromatic polyesterhaving an intrinsic viscosity of 0.50 to 0.90 dl/g, recycled polyesterfrom collected polyethylene terephthalate-based aromatic polyesterarticles, PETG (condensate of ethylene glycol, cyclohexanedimethanol,and terephthalic acid, produced by Eastman), polyethylene, polyethyleneacrylate resins (J-REX EEA and LEXPEARL produced by Japan PolyolefinsCo., Ltd.), toluene, benzene, xylene, and the like may be used. If theresulting articles needs to be transparent, an organic solvent, such asPET-based polyester, PETG (condensate of ethylene glycol,cyclohexanedimethanol, and terephthalic acid, produced by Eastman),toluene, benzene, or xylene, may be used. If the resulting articles doesnot need to be transparent, polyethylene, polyethylene acrylate resins(J-REX EER and LEXPEARL produced by Japan Polyolefins Co., Ltd.) or thelike may be used.

Binder masterbatch D generally contains 10 to 50 parts by weight ofbinder B and 100 parts by weight of base substance C, and preferably 15to 20 parts by weight of binder B and 100 parts by weight of basesubstance C. A binder B content of 10 parts by weight or less degradesthe effect of masterbatch D and increases cost. A binder B content of 50parts by weight or more disadvantageously makes it difficult to preparemasterbatch D, and is liable to cause gel to form during the couplingreaction.

Binder masterbatch D is generally used in an amount of 1 to 10 parts byweight relative to 100 parts by weight of saturated straight-chainpolyester A, and more preferably in an amount of about 5 parts byweight, which improves ease of dispersing and mixing.

In order to prepare binder masterbatch D, a common single screwextruder, a twin screw extruder, a kneader-ruder, or the like having anL/D ratio of about 10 to 45 may be used. A predetermined amount of thebinder is supplied from the side to extrude a strand from a die while apredetermined amount of resin of base substance C is allowed by theextruder to flow at a temperature 10 to 20° C. higher than the meltingpoint of the base substance. After being water-cooled, the strand is cutinto pellets. If the binder is liquid, it is supplied by a metering pumpthrough the vent of the extruder or a forced supply line. If the binderis semisolid or solid, it is supplied by a metering pump while a storagecontainer and a forced supplying line are heated. Alternatively, it maybe dissolved in benzene, toluene, xylene, or the like to a predeterminedconcentration in advance, and is, for example, diluted 2 to 10 times.Then, the diluted binder is supplied. Next, the resulting pellets of thebinder masterbatch D are dried at a temperature equal to or lower thanthe melting point of base substance C and at which the pellets do notadhere to each other, for example, in the range of 50 to 140° C., andpreserved in a three-layered moisture-proof bag composed of aluminium,polyethylene, and paper.

Coupling reaction catalyst E of component (3) contains at least oneselected from the group consisting of (a) alkali metal carboxylates, (b)alkaline-earth metal carboxylates, and (c) aluminium, zinc, andmanganese carboxylates. The metals contained in the metal carboxylatesinclude alkali metals, such as lithium, sodium, and potassium;alkaline-earth metals, such as magnesium, calcium, strontium, andbarium; and other metals, such as aluminium, zinc, and manganese.

The carboxylic acids of the carboxylates include aliphatic carboxylicacids having a carbon number in the range of 1 to 20, and particularlyin the range of 1 to 10; alicyclic carboxylic acids having a carbonnumber in the range of 3 to 12; and aromatic carboxylic acids having acarbon number in the range of 7 to 20. Specifically, the carboxylicacids include acetic acid, propionic acid, butyric acid, caproic acid,adipic acid, stearic acid, palmitic acid, montanic acid,cyclohexanecarboxylic acid, benzoic acid, and phthalic acid. Inparticular, easily available, inexpensive metal acetates and metalstearates (homogeneous catalysts) having a melting point lower than thatof the raw material polyester are preferable.

More preferably, the coupling reaction catalyst E is a composite ofmetal carboxylates and masterbatch G containing these metalcarboxylates. It has been found that metal carboxylates are not alwayssuitable for preparing the polyester of the present invention when theyare used separately. For example, while lithium stearate significantlyreduces MFR, the catalytic activity thereof is low and, therefore,cannot complete a coupling reaction and results in a strand hard todraw. Sodium stearate has a high catalytic activity and therefore cancomplete a coupling reaction, thus resulting in a strand easy to draw(having a nucleation function); however, it changes the target polyestercolor to yellow. Also, calcium stearate has the same functions aslithium stearate and results in a colorless, clear polyester, but thecatalytic activity thereof is further lower. Manganese acetate has acatalytic activity higher than that of sodium stearate and therefore cancomplete a coupling reaction, thus resulting in a strand easy to draw(having a nucleation function); however, it further changes the targetpolyester color to red brown.

It is therefore preferable that the coupling reaction catalyst be acomposite. As for a binary catalyst, catalyst E may, for example, be20/80 to 50/100 of lithium stearate/calcium stearate, 20/80 to 50/100 ofsodium stearate/calcium stearate, 20/100 to 50/100 of manganeseacetate/lithium stearate, or 20/100 to 50/100 of manganeseacetate/calcium stearate. As for a ternary catalyst, catalyst E may, forexample, be a composite catalyst, such as 50/50/100 of lithiumstearate/sodium stearate/calcium stearate, 50/50/100 of lithiumstearate/sodium acetate/calcium stearate, or 50/50/100 of lithiumstearate/manganese acetate/calcium stearate, or a masterbatch containingthe composite catalyst and base substance F.

The carboxylate content of coupling reaction catalyst E, includinglithium salts, sodium salts, calcium salts, and manganese salts, is inthe range of 0.01 to 0.5 parts by weight relative to saturatedstraight-chain polyester A of component (1). Preferably, it is in therange of 0.05 to 0.2 parts by weight. If the content is less than 0.01parts by weight, the catalytic activity becomes low, and the couplingreaction may not be completed, consequently not increasing the molecularweight. A content more than 0.5 parts by weight may by-produce gel orrapidly increase the melt viscosity due to a local reaction, and thuscause hydrolysis or other problems in the extruder or during a moldingprocess.

Another of the most striking characteristics of the present invention isthat, in order to prevent a local reaction at the vicinity of catalystE, masterbatch G is used with base substance F used as a diluent. Asbase substance F, a polyethylene terephthalate-based aromatic polyesterhaving an intrinsic viscosity of 0.50 to 0.90 dl/g, recycled polyesterfrom collected polyethylene terephthalate-based aromatic polyesterarticles, PETG (condensate of ethylene glycol, cyclohexanedimethanol,and terephthalic acid, produced by Eastman), polyethylene, polyethyleneacrylate resins (J-REX EEA and LEXPEARL produced by Japan PolyolefinsCo., Ltd.), polyacrylate resins (including copolymers), and the like maybe used, substantially as in base substance C. If the resulting articlesneeds to be transparent, a PET-based polyester, PETG (condensate ofethylene glycol, cyclohexanedimethanol, and terephthalic acid, producedby Eastman), or polyacrylate resins (including copolymers) may be used.If the resulting articles does not need to be transparent, polyethylene,polyethylene acrylate resins (J-REX EEA and LEXPEARL produced by JapanPolyolefins Co., Ltd.) or the like may be used.

Catalyst masterbatch G generally contains 5 to 25 parts by weight ofcatalyst E and 100 parts by weight of base substance F, and preferably7.5 to 12.5 parts and more preferably 8 to 10 parts by weight ofcatalyst E and 100 parts by weight of base substance F. A catalyst Econtent of 5 parts by weight or less degrades the effect of masterbatchG and increases cost. A catalyst E content of 25 parts by weight or moredisadvantageously makes it difficult to prepare the masterbatch G, andis liable to by-produce gel during the coupling reaction. In addition,it disadvantageously causes resins to hydrolyze during processingprocesses.

Catalyst masterbatch G is generally used in an amount of 0.25 to 10parts by weight relative to 100 parts by weight of saturatedstraight-chain polyester A, and more preferably in an amount of 0.5 to 2parts by weight, which improves ease of dispersing and mixing.

Coupling reaction catalyst E of component (3) may contain additives,such as a promoter, a nucleation agent, and a crystallizationaccelerator, if necessary. The additives include, for example, halides,carbonates, and bicarbonate of alkali metals and alkaline-earth metals,such as lithium chloride, potassium iodide, and potassium carbonate;aryl or alkyl-substituted phosphines, such as tributylphosphine,trioctylphosphine, and triphenylphosphine; and alkali and alkaline-earthmetal salts of saturated fatty acids, such as butyric acid, valericacid, caproic acid, lauric acid, myristic acid, palmitic acid, stearicacid, behenic acid, and montanic acid, and unsaturated fatty acids, suchas crotonic acid, oleic acid, and elaidic acid, including lithium salts,sodium salts, potassium salts, beryllium salts, magnesium salts, calciumsalts, strontium salts, and barium salts. These additives also may beused as a masterbatch in combination with base substance F.

In addition to polyester A of component (1), compound B containing epoxygroups and base substance C of component (2), and metal carboxylate Eand base substance F of component (3), the polyester resin compositionof the present invention may further contain a nucleation agent or afiller, such as talc, calcium carbonate, calcium oxide, kaolin, alumina,or aluminium hydroxide; a reinforcing agent, such as glass fiber, carbonfiber, aramid fiber, or whisker; and a pigment, such as carbon black,antimony oxide, molybdenum disulfide, or titanium oxide. Also, thepolyester resin composition may contain another colorant, a stabilizer,a UV absorbent, an antioxidant, a viscosity adjuster, an antistaticagent, a conducting agent, a fluidizing agent, a mold release agent,another cross-linker, another resin, and the like, if necessary.

For example, antioxidants include hindered phenol antioxidants, such asp-t-butylhydroxytoluene and p-t-butylhydroxyanisole, sulfur antioxidant,such as distearyl thiodipropionate and dilauryl thiodipropionate. Heatstabilizers include triphenyl phosphite, trilauryl phosphite, andtrisnonylphenyl phosphite. UV absorbers include p-t-butylphenylsalicilate, 2-hydroxy-4-thoxybenzophenone,2-hydroxy-4-methoxy-2′-carboxybenzophenone, and2,4,5-trihydroxybutyrophenone. Antistatic agents includeN,N-bis(hydroxyethyl)alkylamine, alkylarylsulfonate, and alkylsulfonate.Flame retardants include hexabromocyclododecane,tris-(2,3-dichloropropyl)phosphate, and pentabromophenylallyl ether.

Productiones of producing the polyester resin of the present inventionapplying a masterbatch method will now be described. Saturatedstraight-chain polyester A of component (1) may be a new normal resin orflakes, grains, powder, chips, melt, or the like of recycled PETbottles. Raw materials of main component polyester prepolymer arepreferably dried at 90 to 140° C. for several hours to over ten hours indehumidified air or hot air. However, if a specific twin screw extruderis used in a high vacuum, drying is not necessary. Three componentsincluding the raw material and the masterbatches are mixed with a mixer,such as a tumble or a Henschel mixer in advance, and are then suppliedto, for example, a high-vacuum twin screw extruder or a single screwextruder to form pellets. Alternatively, the components may be suppliedto a processing apparatus directly connected to the extruder and are,thus, molded into an article at one time.

In this instance, the temperature for heating and melting is preferablybetween the melting pint of the polyester and 350° C., from theviewpoint of controlling the reaction. A temperature of 300° C. or lessis particularly preferable, and a temperature of more than 350° C. islikely to cause the polyester to change color or thermally decompose.

These three components may be simultaneously mixed. Otherwise rawmaterial A of component (1) and masterbatch D acting as binder B ofcomponent (2) may be previously mixed, and then masterbatch G acting ascatalyst E of component (3) is added from the side. Raw material A ofcomponent (1) and masterbatch G acting as catalyst E of component (3)may be previously mixed, and then masterbatch D acting as binder B ofcomponent (2) is added from the side. Even if the raw material is notdried, the three components may be mixed and added at one time.

As a reactor for heat melting, a single screw extruder, a twin screwextruder, a two-stage extruder which is a combination of these twoextruders, or a kneader-ruder may be used, or a self-cleaning type twinscrew reactor, which is used for polycondensation of PET-based polyesterresins, may be used. Since the high-temperature reaction for producingthe polyester resin of the present invention is conducted in theextruder for a short period of about 1 to 10 minutes, preferably, theL/D ratio of the extruder is in the range of about 30 to 50, andparticularly in the range of 38 to 45.

In general, it is preferable that the residence time be short, and, forexample, between 30 seconds and 60 minutes though it depends on theperformance of the extruder. In particular, a residence time in therange of 1.5 to 5 minutes helps increase the molecular weight ofsaturated straight-chain polyester A rapidly, thus reducing the numberof terminal carboxyl groups rapidly. This is probably because couplingreaction catalyst E facilitates the coupling reaction between theterminal carboxyl groups of raw material polyester A and the epoxygroups of binder B containing polyfunctional epoxy components, so thatthe polyfunctional epoxy components help polyester molecules combinewith each other to extend or branch the molecular chains and thusincrease the molecular weight.

If only coupling reaction catalyst E is added to polyester A and heatmelting is performed, the molecular weight does not increase, nor doesthe number of terminal carboxyl groups decrease. If only thepolyfunctional epoxy compounds contained in component B are added andheat melting is performed, the molecular weight does not increase in ashort time because the reaction is slow. Only by allowing threecomponents (1), (2), and (3) to react in the masterbatches containingbase substances C and F, followed by extrusion, the molecular weight,the melt viscosity, and the degree of swelling can be remarkablyincreased and, thus, a resin and an article having uniform quality canbe achieved with enhanced reproducibility.

In general, it is preferable that the recycled PET bottle flakes and newpolyester resin to be used in the above-described reactor be dried, inadvance, by hot air at 110 to 140° C. to reduce the moisture to between100 and 200 ppm, or dried by dehumidified air to reduce the moisture to50 ppm or less. Polyester resins adsorb moisture in air and usuallycontain 3,500 to 6,000 ppm (0.35% to 0.60% by weight) of moisture,depending on the environmental humidity. Drying as in theabove-described manner helps accomplish the object of the presentinvention with reliability.

If undried recycled PET bottle flakes or undried new polyester resin isused as the raw material, the vacuum line of the twin screw extruder issealed with a non-water substance, that is, oil. The degree of vacuum ofthe first vent is set at 13.3×10³ Pa (100 mmHg) or less, preferably at2.6×10² Pa (20 mmHg) or less, and more preferably at 0.4×10² Pa (3 mmHg)or less, and thus the moisture can be removed by vacuum degassingimmediately after the polyester resin is melted.

The polyester resin of the present invention may be subjected toprocessing in accordance with a prior invention (PCT WO 98/44019).Specifically, the processing temperature is set in the range of 260 to290° C.

EXAMPLES

The present invention will be further illustrated with reference toExamples.

The polyester of the present invention was subjected to measurements ofintrinsic viscosity (IV value), MFR (melt flow rate), the degree ofswelling (dilatation), molecular weight, and melt viscosity. Themeasurements were conducted as follows.

(1) Intrinsic Viscosity

Using a solvent mixture containing identical amounts of1,1,2,2-tetrachloroethane and phenol, the measurement was conducted at25° C. with a Cannon-Fenske viscometer.

(2) MFR

In accordance with condition 20 of JIS K 7210, the measurement wasconducted at a temperature of 280° C. and under a load of 2.16 kg.

(3) Degree of Swelling

Using a melt indexer for measuring MFR, samples were allowed to flow anddroop at a temperature of 280° C. and under a load of 2.16 kg until theydrooped 2.0 cm, followed by cutting off. The diameter at a position 5.0mm from the bottom edge of the samples was measured, and the degree ofswelling was derived from the following equation. The measurement wasperformed several times for each sample and the average value of themeasurement was used. The value “2.095” in the following equationrepresents the diameter of the nozzle of the melt indexer for MFRmeasurement.

Degree of swelling (%)=[(average diameter−2.095)/2.095]×100

(4) Molecular Weight

The measurement was performed by a GPC method, using a main unitSYSTEM-21 and two columns Shodex KF-606M (for both sample andreference), each manufactured by Showa Denko K.K.

Solvent: hexafluoroisopropyl alcohol

column temperature: 40° C.

Injection amount: 20 μL Flow rate: 0.6 ml/min

Polymer content: 0.15% by weight

Detector: Shodex RI-74, molecular weight conversion

standard: PMMA (Sodex M-75)

(5) Melt Viscosity

Using the DynAlyser DAR-100 manufactured by REOLOGICA in Sweden, themeasurement was performed by applying torsional vibration between hotplates to sample pieces 2 cm in length and width and 2 mm in thicknessat 280° C. in an atmosphere of nitrogen.

Production Examples 1 to 5 of Masterbatches

Production Examples of Binder Masterbatches D1 to D5

Using a twin screw extruder, manufactured by Berstorff, having anopening diameter of 43 mm and an L/D ratio of 43 and evacuated bythree-stage water-sealing, 50 parts by weight of clear flakes (preparedfrom recycled PET bottles, having a intrinsic viscosity of 0.725 dl/gand a MFR of 56 g/10 min) produced by Yono PET Bottle Recycle Co., Ltd.dried by hot air at 120° C. for about 12 hours and 50 parts by weight ofPETG 6763 (IV: 0.73, density: 1.27) supplied in a dried bag and producedby Eastman were extruded at a set temperature of 260° C., a screwrotation of 200 rpm, a first vent pressure of about −600 mmHg, a thirdvent pressure of about −670 mmHg, and a self-feeding rate of 30 kg/h. Atthe same time, 15 parts by weight of ethylene glycol diglycidyl ether(Epolight 40E produced by Kyoeisha Kagaku Co., Ltd., epoxy equivalent:135 g/eq, lemon yellow liquid), which is a difunctional epoxy compound,was injected from the second vent with a metering pump to serve as abinder (Production Example 1, binder masterbatch D1).

In the same manner, 15 parts by weight of a mixture of 75 parts byweight of difunctional ethylene glycol diglycidyl ether and 25 parts byweight of trifunctional trimethylolpropane triglycidyl ether (Epolight100MF produced by Kyoeisya Kagaku Co., Ltd., epoxy equivalent: 150 g/eq,lemon yellow liquid) was injected with a metering pump to serve as abinder (Production Example 2, binder masterbatch D2). In the samemanner, 15 parts by weight of a mixture of 50 parts by weight ofethylene glycol diglycidyl ether and 50 parts by weight of trifunctionaltrimethylolpropane triglycidyl ether was injected with a metering pump(Production Example 3, binder masterbatch D3). In the same manner, 15parts by weight of a mixture of 25 parts by weight of ethylene glycoldiglycidyl ether and 75 parts by weight of trifunctionaltrimethylolpropane triglycidyl ether was injected with a metering pump(Production Example 4, binder masterbatch D4). In the same manner, 15parts by weight of trifunctional trimethylolpropane triglycidyl etherwas injected with a metering pump (Production Example 5, bindermasterbatch D5).

Five strands extruded from die openings of 3.5 mm in diameter werecooled down in water, and were cut into pellets with a rotary cutter.The resulting pellets in an amount of 100 kg each were dried at 140° C.for about 0.5 hours and subsequently at 120° C. for about 12 hours byhot air, and were then preserved in a moisture-proof bags.

Production Examples 6 and 7 of Masterbatches

Production Examples of Catalyst Masterbatches G1 and G2

Using a twin screw extruder, manufactured by Berstorff, having adiameter of 43 mm and an L/D ratio of 43 and evacuated by three-stagewater-sealing, 50 parts by weight of a dried clear flake (prepared fromrecycled PET bottles, having a intrinsic viscosity of 0.725 dl/g and aMFR of 56 g/10 min) produced by Yono Pet Bottle Recycle Co., Ltd.; 50parts by weight of dried PETG 6763 (IV: 0.73, density: 1.27) produced byEastman; and a composite catalyst containing 2.5 parts by weight oflithium stearate, 2.5 parts by weight of sodium stearate, and 5.0 partsby weight of calcium stearate were mixed in a tumbler (ProductionExample 6, composite catalyst masterbatch G1). While the sample wasbeing extruded at a set temperature of 260° C., a screw rotation of 200rpm, a first vent pressure of about −630 mmHg, a third vent pressure ofabout −730 mmHg, and a self-feeding rate of 30 kg/h, five strands fromdie openings of 3.5 mm in diameter were cooled down in water, and werecut into pellets with a rotary cutter. Each type of resulting pellets inan amount of 10 kg were dried at 140° C. for about 1 hour andsubsequently at 120° C. for about 12 hours by hot air, and were thenpreserved in a moisture-proof bag.

In the same manner, 50 parts by weight of a dried clear flake, 50 partsby weight of PETG 6763 produced by Eastman, a composite catalystcontaining 2.5 parts by weight of lithium stearate and 5.0 parts byweight of calcium stearate, and 2.5 parts by weight of talc acting as anucleation agent were mixed in a tumbler (Production Example 7,composite catalyst masterbatch G2).

Example 1

Formation of a Film by Inflation Techniques, Using Pellets of aPolyester (P1) Having a Low-Long Chain Blanches Prepared by AddingBinder Masterbatch D1 Containing 100% by Weight of a Compound Having TwoEpoxy Groups and Catalyst Masterbatch G1

Using a tumbler, 100 parts by weight of undried clear flakes (preparedfrom recycled PET bottles, having an intrinsic viscosity of 0.725 dl/gand a MFR of 56 g/10 min) produced by Yono PET Bottle Recycle Co., Ltd.;5 parts by weight of the binder masterbatch (D1) of Production Example1; and 4.0 parts by weight of the composite catalyst masterbatch (G1) ofProduction Example 6 containing 50 parts by weight of lithium stearate,50 parts by weight of sodium stearate, and 100 parts by weight ofcalcium stearate were mixed. While the sample was being extruded at aset temperature of 280° C., a number of screw rotation of 100 rpm, afirst vent pressure of about −755 mmHg, a second and third vent pressureof about −690 mmHg, and a self-feeding rate of 30 kg/h with a twin screwextruder PCM-46 manufactured by Ikegai Corporation having an openingdiameter of 46 mm and an L/D ratio of 35 and evacuated by three-stageoil-sealing, five strands extruded from die openings of 3 mm in diameterwere cooled down in water, and were cut into pellets with a rotarycutter. The resulting pellets were dried at 120° C. for about 12 hoursand were preserved in a moisture-proof bag.

The resulting polyester resin pellets (P1) having a small number oflong-chain branches exhibited an intrinsic viscosity of 0.85 dl/g, a MFRof 14.5 g/10 min, a degree of swelling of 45%, and a melt viscosity of1,300 Pa·s.

The polyester resin pellets (P1) having a small number of branchedchains taken from the moisture-proof bag were subjected to molding witha LDPE inflation film-forming apparatus manufactured by Topy Industries,Ltd. operated by a single screw and having an opening diameter of 50 mmand an L/D ratio of 32 under the conditions of a die diameter of 100 mm,a lip gap of 1.0 mm, a temperature of 270° C., and an blow ratio of 2.9.Thus, a transparent film having a thickness of about 30 microns wasobtained. This film barely exhibited any by-production of gel andfisheyes in comparison with the known method where neither a bindermasterbatch nor a composite catalyst is used. In contrast, in formationusing recycled PET bottle flakes, the sample flowed out from the outletsof a die like water, consequently not resulting in a film.

Example 2

Direct Formation of Sheet While a Polyester (P2) Having a MiddleLong-Chain Branches was Prepared by Adding Binder Masterbatch D2Containing 75% by Weight of a Compound Having Two Epoxy Groups and 25%by Weight of a Compound Having Three Epoxy Groups and a Catalyst

Using a tumbler, 100 parts by weight of an undried clear flakes(prepared from recycled PET bottles, having an intrinsic viscosity of0.726 dl/g and a MFR of 52 g/10 min) produced by With PET Bottle RecycleCo., Ltd.; 2.5 parts by weight of the binder masterbatch (D2) of Example2; and powder composite catalyst containing 0.1 parts by weight oflithium stearate, 0.05 parts by weight of sodium stearate, and 0.05parts by weight of calcium stearate were mixed. A twin screw extruderfor the first stage having an opening diameter of 46 mm and an L/D ratioof 35, evacuated by three-stage oil-sealing, and being set at atemperature of 280° C., a screw rotation of 100 rpm, a first ventpressure of about −755 mmHg, a second and third vent pressure of about690 mmHg, and a self-feeding rate of 60 kg/h; a single screw extruderPS-65 for the second stage having an opening diameter of 65 mm and anL/D ratio of 25, being set at a temperature of 270° C., a screw rotationof 85 rpm; a T die having a width of 650 mm and a lip gap of 1.5 mm; anda horizontal-type, and three-stage vertical oil-heating chill roll wereused.

Colorless, transparent sheets of 580 mm in width and 0.8 mm in thicknesswere obtained by horizontal drawing. In the sheets, gel and fisheye werebarely present in comparison with the known method in which neither abinder masterbatch nor a composite catalyst is used. The MFR of theresulting sheet was 16. In tensile tests (50 mm/min) using a number 2dumbbell specified in JIS, the sheets exhibited yield strengths of 575kgf/cm² (MD) and 587 kgf/cm² (TD), break strengths of 587 kgf/cm² (MD)and 504 kgf/cm² (TD), break elongations of 370% (MD) and 670% (TD), andtensile modulus of 280 kgf/mm² (MD) and 250 kgf/mm² (TD).

Examples 3 to 6

Preparation of Pellets of High-molecular-weight Polyester Resins (P3 toP6) by Adding Any One of Masterbatches D2 to D5 Containing Difunctionaland Trifunctional Aliphatic Binders and Composite Catalyst MasterbatchG1

Three types of materials were mixed in a tumbler. The materials were 100parts by weight of undried clear flakes (prepared from recycled PETbottles, having an intrinsic viscosity of 0.725 dl/g, a MFR of 56 g/10min, and a melt viscosity of 67 Pa·s, quality specification:respectively under 30 ppm of aluminium and metals, 40 ppm of PVC flakes,450 ppm of pigment flakes, 30 ppm of polyolefin, and 90 ppm of a labeland others) produced by Yono PET Bottle Recycle Co., Ltd., 7.0 parts byweight of any one of the binder masterbatches (D2 to D5) of respectiveProduction Examples 2 to 5, and 1.1 parts by weight of the compositecatalyst masterbatch (G1) of Production Example 1 containing 50 parts byweight of lithium stearate, 50 parts by weight of sodium stearate, and100 parts by weight of calcium stearate. While samples were beingextruded at a set temperature of 280° C., a screw rotation of 100 rpm, afirst vent pressure of about −750 mmHg, a second and third vent pressureof about 755 mmHg, and a self-feeding rate of 50 kg/h with a twin screwextruder PCM-70 manufactured by Ikegai Corporation having an openingdiameter of 70 mm and an L/D ratio of 37 and evacuated by three-stageoil-sealing, ten strands extruded from die openings of 2 mm in diameterwere cooled down in water, and were cut into pellets with a rotarycutter. Each type of resulting pellets in an amount of 100 kg was driedat 120° C. for about 12 hours by hot air, and was preserved in amoisture-proof bag.

These types of resulting high-molecular-weight PET resin pelletsexhibited the following respective MFRs and melt viscosities (280° C.):6.5 g/10 min and 5,500 Pa·s (P3); 3.2 g/10 min and 21,000 Pa·s (P4); 2.6g/10 min and 35,000 Pa·s (P5); and 1.0 g/10 min and 95,000 Pa·s (P6).

For the sake of comparison, the respective IV values, MFRs, and meltviscosities of commercially available pellets were: 0.72 dl/g, 57 g/10min, and 70 Pa·s (C1); 0.83 dl/g, 22.7 g/10 min, and 190 Pa·s (C2); 1.0dl/g, 14 g/10 min, and 220 Pa·s (C3); and 1.19 dl/g, 8.3 g/10 min, and2,500 Pa·s (C4). In terms of the high-molecular-weight grades,commercially available PETs had melt viscosities lower than that of thepellets of the present invention and were, therefore, of inferiorprocessability.

Production Examples 8 to 11 for Masterbatches

Production Examples of Masterbatches D6 to D11

Using a twin screw extruder, manufactured by Berstorff, having anopening diameter of 43 mm and an L/D ratio of 43 and evacuated bythree-stage water-sealing, 70 parts by weight of a clear flake (preparedfrom recycled PET bottles, having an intrinsic viscosity of 0.725 dl/gand a MFR of 56 g/10 min) produced by Yono PET Bottle Recycle Co., Ltd.dried by hot air at 120° C. for about 12 hours and 30 parts by weight ofa PET resin (IV: 0.83, density: 1.35) supplied in a dried bag andproduced by Unitika Ltd. were extruded at a set temperature of 260° C.,a screw rotation of 200 rpm, a first vent pressure of about −600 mmHg, athird vent pressure of about −670 mmHg, and a self-feeding rate of 30kg/h. At the same time, 15 parts by weight of an epoxide soybean oil(epoxy plasticizer O-130P produced by Asahi Denka Co., Ltd., epoxyequivalent: 232 g/eq, lemon yellow liquid), which is a polyfunctionalepoxy compound having more than two epoxy groups, was injected from thesecond vent with a metering pump to serve as a binder (ProductionExample 8, binder masterbatch D6).

In the same manner, 15 parts by weight of an epoxide linseed oil (anepoxy plasticizer O-180A produced by Asahi Denka Co., Ltd., epoxyequivalent: 176 g/eq, light yellow liquid), which is a polyfunctionalepoxy compound having more than two epoxy groups was injected with ametering pump to serve as a binder (Production Example 9, bindermasterbatch D7). In the same manner, 15 parts by weight of a heat-stablepentafunctional epoxy compound having more than two epoxy groups (abiphenyldimethane epoxy resin, NC 3000S, produced by Nippon Kayaku Co.,Ltd., epoxy equivalent of 275 g/eq, light yellow semisolid) was injectedwith a metering pump to serve as a binder (Production Example 10, bindermasterbatch D8).

Five strands extruded from die openings of 3.5 mm in diameter werecooled down in water, and were cut into pellets with a rotary cutter.Each type of resulting pellets in an amount of 50 kg was dried at 140°C. for about 0.5 hours and subsequently at 120° C. for about 12 hours byhot air, and then preserved in a moisture-proof bag.

On the other hand, 50 parts by weight of toluene and 50 parts by weightof a mixture containing 70 parts by weight of difunctional ethyleneglycol diglycidyl ether and 30 parts by weight of trifunctionaltrimethylolpropane triglycidyl ether were mixed in a stainless vessel toprepare a liquid masterbatch (Production Example 11, binder masterbatchD9).

Examples 7 to 9

Preparation of Pellets of High-molecular-weight Polyester Resins (P7 toP9) by Adding Any One of Binder Masterbatches D6 to D9 Containing 100Parts by Weight of Polyfunctional Epoxy Compounds and Composite CatalystMasterbatch G1

Three types of materials were mixed in a tumbler. The materials were 100parts by weight of undried clear flakes (prepared from recycled PETbottles, having an intrinsic viscosity of 0.725 dl/g and a MFR of 56g/10 min, quality specification: respectively under 30 ppm of aluminiumand metals, 40 ppm of a PVC flakes, 450 ppm of pigment flakes, 30 ppm ofpolyolefin, and 90 ppm of a label and others) produced by Yono PETBottle Recycle Co., Ltd., 10 parts by weight of any one of the bindermasterbatches (D6 to D8) of respective Production Examples 8 to 10, and1.0 parts by weight of the composite catalyst masterbatch (G1) ofProduction Example 6 containing 50 parts by weight of lithium stearate,50 parts by weight of sodium stearate, and 100 parts by weight ofcalcium stearate. While samples were being extruded at a set temperatureof 280° C., a screw rotation of 100 rpm, a first vent pressure of about−755 mmHg, a second and third vent pressure of about −750 mmHg, and aself-feeding rate of 15 kg/h with a twin screw extruder PCM-46manufactured by Ikegai Corporation having a diameter of 46 mm and an L/Dratio of 35 and evacuated by three-stage oil-sealing, five strands fromdie openings of 3 mm in diameter were cooled down in water, and were cutinto pellets with a rotary cutter. Each type of resulting pellets in anamount of 20 kg was dried by hot air at 120° C. for about 12 hours, andpreserved in a moisture-proof bag.

The MFRs of the respective types of the resulting high-molecular-weightPET resin pellets were 18 g/10 min (P7), 15 g/10 min (P8), and 10 g/10min (P9).

Comparative Examples 1 to 3

Preparation of PET Resin Pellets Having a Middle Long-chain Branches byUsing a Single Catalyst and Binder Masterbatch D2 Containing 75% byWeight of a Difunctional Epoxy Compound and 25% by Weight of aTrifunctional Epoxy Compound, Without Using Composite CatalystMasterbatch G1

Under the same conditions as in Example 3, composite catalystmasterbatch G1 was replaced with 0.1 parts by weight of lithium stearate(Comparative Example 1), 0.1 parts by weight of sodium stearate(comparative Example 2), or 0.1 parts by weight of calcium stearate(Comparative Example 3). The MFR of Comparative Example 1, in whichlithium stearate was used, was as low as expected, but strands wereliable to cut off seriously. The MFR of Comparative Example 2, in whichsodium stearate was used, was lower than expected, but strands can bedrawn. However, the resulting pellets were undesirably colored yellow.The MFR of Comparative Example 3, in which calcium stearate was used,was far lower than expected, and it was difficult to draw strands.However, the resulting pellets were advantageously colored white.Therefore, composite catalyst masterbatch G1 containing these threetypes of catalysts reduces the MFR as well as expected and facilitatesthe drawing of strands, with a high level of safety. The resultingpellets are advantageously less colored, and barely cause gels toby-produce.

Example 10

Preparation of Pellets of a PET Resin (P10) Having a Low MFR and aMiddle Long-chain Branches by Adding Liquid Binder Masterbatch D9Containing 70% by Weight of a Difunctional Epoxy Compound and 30% byWeight of a Trifunctional Epoxy Compound and a Catalyst, and byLong-Period Operation

Using a tumbler, 100 parts by weight of undried clear flakes (preparedfrom recycled PET bottles, having an intrinsic viscosity of 0.726 dl/gand an MFR of 52 g/10 min) produced by With PET Bottle Recycle Co., Ltd.and composite catalyst masterbatch G1 containing 0.1 parts by weight oflithium stearate, 0.05 parts by weight of sodium stearate, and 0.05parts by weight of calcium stearate were mixed. A twin screw extrudermanufactured by Ikegai Corporation was used which has an openingdiameter of 70 mm and an L/D ratio of 37 and is evacuated by three-stageoil-sealing and which was set at a temperature of 280° C., a screwrotation of 100 rpm, a first vent pressure of about −755 mmHg, a thirdvent pressure of about −750 mmHg, and a self-feeding rate of 50 kg/h.While liquid binder masterbatch D9 was injected into a second vent witha metering pump at a rate of 7.5 kg/h (effective content: 7.5 parts byweight), continuous granulation were performed for three days. A PETresin (P10) having a MFR of 1 to 2 g/10 min and middle long-chainbranches was stably produced.

Comparative Example 10

In substantially the same manner as Example 10, while, instead of liquidbinder masterbatch D9, a raw binder mixture containing 70 parts byweight of difunctional ethylene glycol diglycidyl ether and 30 parts byweight of trifunctional trimethylolpropane triglycidyl ether wasinjected into a second vent at a rate of 3.75 kg/h (effective content:7.5 parts by weight) with a metering pump, continuous granulation wereperformed for three days. The injection line was clogged in the secondday. In advance of this, a pulsing stream of strands and by-productionof dark brown gel occurred. This twin screw extruder was overhauled, anddark brown burnt deposit was found at the second vent and dark brown gelwas found in the vicinity of the third vent. Also, the liquid bindervaporized was condensed in the oil trap of the vacuum line of the thirdvent.

Production Example 12

Production Example of Catalyst Masterbatch G3

Using a twin screw extruder, manufactured by Berstorff, having a openingdiameter of 43 mm and an L/D ratio of 43 and evacuated by three-stagewater-sealing, 50 parts by weight of low-density polyethylene (J-REXF124Z produced by Japan Polyolefins Co., Ltd., MI: 0.4) of clear flakes(prepared from recycled PET bottles, having a intrinsic viscosity of0.725 dl/g and a MFR of 56 g/10 min) produced by Yono PET Bottle RecycleCo., Ltd.; 50 parts by weight of ethylene-acrylate copolymer (J-REX•EEAA1100 produced by Japan Polyolefins Co., Ltd., MI: 0.4); and a compositecatalyst containing 2.5 parts by weight of lithium stearate, 2.5 partsby weight of manganese acetate, and 5.0 parts by weight of calciumstearate were mixed in a tumbler (Production Example 12, compositecatalyst masterbatch G3). While the sample was being extruded at a settemperature of 260° C., a screw rotation of 200 rpm, a first ventpressure of about −630 mmHg, a third vent pressure of about −730 mmHg,and a self-feeding rate of 30 kg/h, five strands from die openings of3.5 mm in diameter were cooled down in water, and were cut into pelletswith a rotary cutter. The resulting pellets in an amount of 10 kg weredried at 140° C. for about 1 hour and subsequently at 120° C. for about12 hours by hot air, and were then preserved in a moisture-proof bag.

Examples 11 and 12

Formation of Sheets by Carbon-dioxide Foaming From the Pellets of PETResin P3 Having a Low MFR and a High Long-chain Branches, or From aSynthesized PET Resin Corresponding to PET Resin P3

In Example 11, the PET resin pellets(P3) of Example 3 having a low MFR(MFR: 6.5 g/10 min) and a high long-chain branches was used to formsheets by carbon-dioxide foaming. A twin screw extruder (diameter: 60mm, L/D: 40, vacuumed by two-stage oil sealing) equipped with acarbon-dioxide injector, a gear pump, a circle die (opening diameter: 85mm, gap: 0.5 mm), a mandrel cooler, and a taking-up device was used.Under the conditions where the twin screw extruder or the like was setat a temperature of 260 to 250° C., a number of screw rotation of 100rpm, a first vent pressure of about 5 mmHg, a second vent pressure ofabout 5 to 10 mmHg, and a self-feeding rate of 50 kg/h, while the PETresin (P3) was supplied, 3 parts by weight of carbon dioxide wasinjected relative to 100 parts by weight of the resin. Thus, foamedsheets having a expanded ratio of 4 times, a foam diameter of 0.5 mm, athickness of 2 mm, and a width of 600 mm were obtained.

In Example 12, sheets were formed directly from a synthesized PET resincorresponding to the pellets of the PET resin (P3) having a low MFR anda high long-chain branches by carbon-dioxide foaming.

Using a tumbler, 100 parts by weight of an undried clear flakes(prepared from recycled PET bottles, having an intrinsic viscosity of0.725 dl/g and a MFR of 56 g/10 min) produced by Yono PET Bottle RecycleCo., Ltd., 7.5 parts by weight of the binder masterbatch (D2) ofProduction Example 2, 2.0 parts by weight of the composite catalystmasterbatch (G3) of Production Example 12 containing 50 parts by weightof lithium stearate, 50 parts by weight of manganese acetate, and 100parts by weight of calcium stearate, and 2.0 parts by weight of talcparticles acting as a nucleation agent were mixed. The operation wasperformed using the same equipment and under substantially the sameconditions as in Example 11. Thus, foamed sheets having a expanded ratioof 4.5 times, a foam diameter of 0.3 mm, a thickness of 2 mm, and awidth of 600 mm were obtained.

Example 13

Formation of Pipes From a PET Resin (P11) Having a Low MFR and a HighLong-chain Branches

Using a tumbler, 100 parts by weight of undried clear flake (preparedfrom recycled PET bottles, having an intrinsic viscosity of 0.726 dl/gand a MFR of 52 g/10 min) produced by With PET Bottle Recycle Co., Ltd.;7.5 parts by weight of the binder masterbatch (D3) of Example 3; 2.5parts by weight of talc; and 1.1 parts by weight of the compositecatalyst masterbatch (G2) containing 5.0 parts by weight of lithiumstearate and 5.0 parts by weight of calcium stearate were mixed. A twinscrew extruder for the first stage having an opening diameter of 46 mmand an L/D ratio of 35, evacuated by three-stage oil-sealing, and beingset at a temperature of 280° C., a screw rotation of 100 rpm, a firstvent pressure of about −755 mmHg, a second and third vent pressure ofabout −690 mmHg, and a self-feeding rate of 30 kg/h; a single screwextruder for the second stage having an opening diameter of 65 mm and anL/D ratio of 25, being set at a temperature of 270° C., a screw rotationof 50 rpm; and a circle die of 50 mm having a lip gap of 1.5 mm wereused to perform horizontal extrusion and water cooling. Thus, pipeshaving an external diameter of 50 mm were obtained.

Example 14

Formation of Injection-molded Articles From a Pet Resin (P1) Having aMiddling Molecular Weight and a Low Long-chain Branches and a RecycledPET Flake

Using an injection molding apparatus equipped with a twin screwextruder, a small container was formed by injection molding from 50parts by weight of a PET resin (P1) having a middling molecular weightand a low long-chain branches and 50 parts by weight of a PET flakecollected from a compressed air molding factory for A-PET sheets.

INDUSTRIAL APPLICABILITY

By applying the masterbatch method of the present invention, thePET-based polyester of the present invention can be allowed to reactuniformly in long period operation. Since a uniform reaction resinhaving a high molecular weight and a high melt viscosity and degree ofswelling can be obtained, a high-quality articles can be achieved. Theresulting articles has excellent mechanical properties such as thermalstability and tensile strength, and it can be advantageously used asfilms, sheets, foamed materials, pipes, cushioning, heat insulators,packaging materials, food containers, partition plates, and the like inmany industrial fields, such as civil engineering and construction,electrical and electronic, automotive, commodity, packing, and foodpacking industries. Also, a large amount of recycled PET bottlesgenerated in large quantity can effectively be used as a prepolymer, andthis is advantageous to society. In addition, the combustion heat valueis as low as half the combustion heat value of polyethylene andpolypropylene when the resin is burned after use, and thereforeincinerators are less damaged and toxic gases are not generated.

What is claimed is:
 1. A masterbatch method for producing a polyesterresin, comprising the step of allowing materials to react uniformly at atemperature equal to or greater than the melting point of a polyester A,the materials comprising: (1) 100 parts by weight of saturatedstraight-chain polyester A; (2) 1 to 10 parts by weight of bindermasterbatch D comprising: 10 to 5 parts by weight of a mixture acting asa binder containing 0 to 100 parts by weight of a compound having twoepoxy groups in the molecule thereof and 100 to 0 parts by weight of acompound having an average number of epoxy groups of 2.1 or more; and100 parts by weight of base substance C; and (3) 0.25 to 10 parts byweight of catalyst masterbatch G comprising: 5 to 25 parts by weight ofa metal carboxylate acting as coupling reaction catalyst E; and 100parts by weight of base substance F, whereby the melt viscosity of thepolyester increases so that the melt flow rate (MFR) is 50 g/10 min orless at 280° C. and under a load of 2.16 kgf in accordance withcondition 20 of JIS K 7210, and the degree of swelling of the polyesterincreases to between 5% and 200%.
 2. A masterbatch method for processingan article, comprising the steps of molding a polyester resin preparedby the method according to claim 1 into pellets in advance; and moldingthe pellets into the articles.
 3. A masterbatch method for processing anarticle, comprising the step of introducing a polyester resin preparedby the method according to claim 1 to a die or a mold to form thearticles immediately after the reaction of claim
 1. 4. A masterbatchmethod for producing a polyester resin or an article of the polyesterresin according to claim 1, wherein saturated straight-chain polyester Ais a polyethylene terephthalate-based aromatic polyester having anintrinsic viscosity in the range of 0.50 to 0.90 dl/g when the intrinsicviscosity is measured at 25° C. after the polyethyleneterephthalate-based aromatic polyester is dissolved in1,1,2,2-tetrachloroethane:phenol (1:1) solvent mixture.
 5. A masterbatchmethod for producing a polyester resin or an article of the polyesterresin according to claim 1, wherein saturated straight-chain polyester Ais a recycled material prepared from collected polyethyleneterephthalate-based aromatic polyester articles.
 6. A masterbatch methodfor producing a polyester resin or an article of the polyester resinaccording to claim 1, wherein the compound having two epoxy groups inthe molecule thereof contained in binder B of binder masterbatch Dcontains at least one selected from the group consisting of alkyleneglycol diglycidyl ether, poly alkylene glycol diglycidyl ether,alicyclic hydrogenated bisphenol A diglycidyl ether, and aromaticbisphenol A diglycidyl ether and early condensates of bisphenol Adiglycidyl ether.
 7. A masterbatch method for producing a polyesterresin or an article of the polyester resin according to claim 1, whereinthe compound having an average number of epoxy groups of 2.1 or morecontained in binder B of binder masterbatch D contains at least oneselected from the group consisting of: aliphatic trimethylolpropanetriglycidyl ether, glycerin triglycidyl ether, epoxide soybean oil, andepoxide linseed oil; heterocyclic triglycidyl isocyanurate; and aromaticphenol novolac epoxy resins, cresol novolac epoxy resins, andbisresorcinol tetraglycidyl ether.
 8. A masterbatch method for producinga polyester resin or an article of the polyester resin according toclaim 1, wherein base substance C of binder masterbatch D contains atleast one selected from the group consisting of a polyethyleneterephthalate-based aromatic polyester having an intrinsic viscosity inthe range of 0.50 to 0.90 dl/g when the intrinsic viscosity is measuredat 25° C. after the polyethylene terephthalate-based aromatic polyesteris dissolved in 1,1,2,2-tetrachloroethane:phenol (1:1) solvent mixture,a recycled material prepared from collected polyethyleneterephthalate-based aromatic polyester articles, condensates of ethyleneglycol, cyclohexanedimethanol, and terephthalic acid, polyethyleneacrylate resins, and toluene.
 9. A masterbatch method for producing apolyester resin or an article of the polyester resin according to claim1, wherein coupling reaction catalyst E of catalyst masterbatch G is acomposite containing at least two selected from the group consisting oflithium salts, sodium salts, potassium salts, magnesium salts, calciumsalts, zinc salts, and manganese salts of stearic acid and acetic acid.10. A masterbatch method for producing a polyester resin or an articleof the polyester resin according to claim 1, wherein base substance F ofcatalyst masterbatch G contains at least one selected from the groupconsisting of a polyethylene terephthalate-based aromatic polyesterhaving an intrinsic viscosity in the range of 0.50 to 0.90 dl/g when theintrinsic viscosity is measured at 25° C. after the polyethyleneterephthalate-based aromatic polyester is dissolved in1,1,2,2-tetrachloroethane:phenol (1:1) solvent mixture, a recycledmaterial prepared from collected polyethylene terephthalate-basedaromatic polyester articles, condensates of ethylene glycol,cyclohexanedimethanol, and terephthalic acid, and polyethylene acrylateresins.
 11. A masterbatch method for producing polyester resin pellets,comprising the steps of: melting (1) undried saturated straight-chainpolyester A at a temperature more than or equal to the melting pointthereof while performing dehydration by degassing to a pressure of13.3×10³ Pa or less in a non-water-sealed vacuum line; allowing (2)binder masterbatch D and (3) coupling reaction catalyst masterbatch G touniformly react together by heating, so that the resulting polyesterresin has a melt flow rate (MFR) of 50 g/10 min or less at a temperatureof 280° C. under a load of 2.16 kgf in accordance with condition 20 ofJIS K 7210, and has a degree of swelling of 5% to 200%; and pelletizingthe resulting polyester resin.
 12. A masterbatch method for producing anarticle, comprising the steps of: melting (1) undried saturatedstraight-chain polyester A at a temperature more than or equal to themelting point thereof while performing dehydration by degassing to apressure of 13.3×10³ Pa or less in a non-water-sealed vacuum line;allowing (2) binder masterbatch D and (3) coupling reaction catalystmasterbatch G to uniformly react together by heating, so that theresulting polyester resin has a melt flow rate (MFR) of 50 g/10 min orless at a temperature of 280° C. under a load of 2.16 kgf in accordancewith condition 20 of JIS K 7210, and has a degree of swelling of 5% to200%; and introducing the resulting polyester to a die or a mold to formthe article immediately after the foregoing reaction.